1. Field of the Invention
The present invention relates to the process to transfer the data consisting of a plurality of records among the computers connected with a network or an input/output channel
2. Description of the Related Art
Following two kinds of technologies have been proposed as the prior arts for transferring the data consisting of many records between a couple of computer nodes.
The first related art is described from the line 61 to the line 81 on the page 2 of the Japanese Laid-Open Publication No. H6-67944. This first related art discloses a method of using a common disc drive for a couple of computer nodes. In this method, a set consisting of two volumes storing the same data is prepared and each volume is respectively connected to each computer node for the purpose of common use. When one computer node desires to refer to the data, it releases the set of volumes (separation of volumes) and causes the computer node in the side for reference to occupy one volume (hereinafter, referred to as the first volume). During this period, a controller for this disc records all changes by the other computer node to another volume (hereinafter, referred to as the second volume). When the computer node that has referred to the data completes the reference to release occupation of the first volume, the controller for the disc explained above reflects the record of changes for the second volume on the first volume and thereafter places these two volumes to the condition for common use from two computer nodes as a set of storing the same data (re-synchronization of volumes).
The second related art is described from the line 58 on the page 3 to the line 52 on the page 4 of the Japanese Laid-Open Publication No. HEI 6-149485. In this second related art, a semiconductor external storage device is used for the common use among the computer modes. In this method, single memory area is used in common among a plurality of computer nodes and each computer node exclusively accesses such memory area.
Here, the first related art is required to execute separation of volumes and re-synchronization each time when one computer node refers to the data. Therefore, this related art has a problem that it cannot be easily adapted to the real-time process due to its response time.
On the other hand, the second related art is required to execute, for each data transfer, to execute exclusive control for the areas in the computer nodes in the data output side and the data reference side in order to assure the perfection of the records. On the occasion of transferring a large amount of data, there is a problem that the overhead that is required for these exclusive processes becomes large in the number. Moreover, this overhead sometimes lowers the data transfer efficiency.